1. Field of the Invention
This invention relates to a conjugated diene copolymer, a process for producing the copolymer, and a photosensitive composition comprising the copolymer.
2. Discussion of the Background
Synthetic resins have hitherto been used as vehicles for coatings and inks or as adhesives. However, when the coating surface and the adhering surface are flexible, ordinary synthetic resins are unsuitable for applying to the surface, and it is necessary to use a resin having a rubber elasticity, namely, a rubber. Hence, ordinary acrylic rubbers and diene rubbers are used in the form of a solution in an organic solvent because they are inherently insoluble in water and also insoluble in aqueous alkali or acid solutions.
Many organic solvents are harmful to the human body and are inflammable. Therefore, if the organic solvents could be replaced by an aqueous solvent, it would be very advantageous from an aspect of a safety.
As resins soluble in aqueous solvents, carboxyl group-containing polymers are known. However, these polymers have been inferior in rubber elasticity as well as in transparency required for paints, for vehicles of inks and for adhesives.
As a component for a photosensitive composition for use in photoresists, there is proposed a conjugated diene copolymer soluble in aqueous alkali solutions (Japanese Patent Publication No. 1,140/83, U.S. Pat. No. 4,275,142). This copolymer is insufficient in transparency and further requires an improvement in rubber elasticity. Furthermore, the copolymer is insufficient also in photosetting property.
Recently, there has been proposed a photosensitive resin composition comprising (I) a copolymer comprising (A) a conjugated diolefin (diene) hydrocarbon, (B) an .alpha.,.beta.-ethylenically unsaturated carboxylic acid, and optionally (C) a monoolefinically unsaturated compound, (II) a photopolymerizable unsaturated monomer and (III) a photosensitizer (Japanese Patent Publication No. 29,849/84, U.S. Pat. No. 4,275,142). However, it has been found that this photosensitive resin composition has various advantages but is not satisfactory in transparency and processability.